Why must the samples be homogeneously ground before actual analysis?

Answer 1

The goal of analysis is to accurately describe the material. Imagine taking a material. You sample it by taking a few grams. You want to be sure your results are reproduciable, so you perform 3 diffferent analyses using 3 different samples. The only way to assure your answers are actually representative of the material is to make sure that any sample taken will be identical to any other sample. The only way to assure that these samples will all be the same, is to make the original material homogenous (uniform).

Imagine taking a bowl of nuts: peanuts, cashews, and almonds. You want to measure the relative % of each type of nut. If you just dump 3 cans on top of one another, before taking a sample, you won't get the same relative concentration of nuts with different samples. It would depend on how deep into the nut mixture your reached, since there would be 3 different layers of nuts. If you stirred the nut mixture for a few minutes, you would make a more uniform mixture. Now, if you sample it, you are more likely to get the same mix of nuts in each sample.

Same thing goes for basic chemicals.

Answer 2

to ensure the conclusions drawn from analysis are truly representitive of the entire sample and not just a part. it's called validity.

Answer 3

So as to get the comparable results and to get the correct one.

Answer 4

So that your analysis is accurate.